In the aforementioned patents and application, I have described the arc-vapor deposition of metals on a substrate, whereby an electric arc is struck between two electrodes, at least one of which can comprise silicon which may ultimately be incorporated in the material to be deposited on the substrate. The arc is struck by approaching one of the electrodes to the other until contact is substantially established, whereupon the electrodes are separated so that an arc is generated between them and causes the evaporation of the material from the one electrode so that this material in the elemental or compound state in which it was originally found in the electrode, is deposited upon the substrate or can undergo reaction with gaseous components in the evacuated space in which the vaporization takes place, or reaction with metal of the other electrode, to deposit as part of a compound or alloy upon the substrate.
In accordance with these principles, a relatively high vacuum is maintained in the region at which the arc is struck and which has been juxtaposed with the substrate. The arc is controlled and striking is repeated to provide reproducible conditions at an appropriate rate.
The silicon can be deposited in elemental form or as a compound and for many purposes, it is desirable or essential to use high purity silicon as a source of the material to be deposited.
When, however, monocrystalline silicon electrodes are fabricated for this purpose, i.e. for vapor deposition of elemental silicon or compound such as silicon carbide or silicon nitride, it is found that the thermal shock resulting from arc striking causes cracking and rupture of the highly frangible material. The phenomenon is equally noticeable with certain other crystalline materials, namely silicon carbide and silicon nitride.
It is, therefore, a drawback of the earlier described systems that deterioration of the electrode, a relatively high-cost item for the process, occurs and is most pronounced when such crystalline materials are the electrode materials of choice.